package com.laoxu.java.util;

import java.security.MessageDigest;

/**
 * MD5加密与认证
 *
 * @author laoxu
 * @create 2018-05-19
 **/
public class MD5Util {
    private final static String[] hexDigits = {"0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f"};

    /**
     * 转换字节数组为16进制字串
     *
     * @param b 字节数组
     * @return 16进制字串
     */
    public static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
            n = 256 + n;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    /**
     * 加密
     *
     * @param origin
     * @return
     */
    public static String MD5Encode(String origin) {
        String resultString = null;
        try {
            resultString = new String(origin);
            MessageDigest md = MessageDigest.getInstance("MD5");
            resultString = byteArrayToHexString(md.digest(resultString
                    .getBytes()));
        } catch (Exception ex) {
        }
        return resultString;
    }

    /**
     * 认证
     *
     * @param input
     * @param output
     * @return
     */
    public static boolean isValidate(String input, String output) {

        boolean status = false;

        if (MD5Util.MD5Encode(input).equals(output)) {
            status = true;
        } else {
            status = false;
        }

        return status;
    }


    public static void main(String[] args) {

        System.out.println(MD5Encode("123"));

        boolean b = MD5Util.isValidate("123", "21232f297a57a5a743894a0e4a801fc3");
        System.out.println(b);

    }
}
